His work, along with that of the rest of the team, is aimed at providing tools and instruments to keep European seas clean, healthy and productive. As you’ll read below our conversation focused mainly on plastic waste, which is by far the biggest contributor to all ocean debris, and is at the core of Dr Watts’ research.

Could you tell us a little about what you do?

I am a researcher based in the Environmental biology research team at the University of Exeter in the United Kingdom.

My research is focused on the effect plastic is having on marine animals. I’m involved with marine life across a range of scales, from studies looking at crabs, commercially important mussels all the way down to bacteria. I have also been looking at the types and sources of plastic getting into our seas and oceans.

How does plastic waste end up in the sea, and what happens when it’s there?

Plastic is getting into our seas and oceans in a few different routes. Some large plastics (anything from a sweet wrapper to a 60 meter fishing net) are ending up there by accident, but some is deliberately disposed of in this way. On the beaches around the South West of the UK, maritime activity (fishing and shipping) makes up between 30-70% of all litter we find. Tourism litter is also a big contributor where in the summer on some beaches it can make up to 26% of all litter items.

It can be difficult to pinpoint the source of all of the plastic litter we find on beaches or in the ocean. The majority of litter found on our beaches is uncategoricizable, where plastic fragments have broken down from large pieces so we cannot determine their source.

As plastic fragments into smaller and smaller pieces due to wave action and UV degradation they turn into what is termed microplastic (<5mm long). Along with this breakdown there is another route of entry into the sea which is through our drainage system. Microplastic is used in many applications; in face washes as exfoliates and used to sandblast buildings. These are entering our drains and not being caught by the waste water treatment works.

What impact does this have on marine life?

Microplastic by its definition is small. It’s small enough to be mistaken for food items for filter feeders such as mussels and has even been shown to be consumed by tiny animals at the base of the food chain (zooplankton). Larger microplastics have been found in seabirds, turtles and whales around the world.

Plastic can block gut passages and transfer toxic chemicals in to animal tissues. The work is ongoing to determine the full impact this has on marine life, but the effects are far reaching. Over 140 species have been detected with microplastics in their guts and there are an estimated 5.5 trillion pieces of plastic in surface waters alone. We are really just starting to understand the effects.

What impact does this have on us?

It is difficult to assign a direct effect to the human population at this stage, but there are likely to be three major effects of plastic in our oceans.

There is an aesthetic impact and the impact on marine tourism. Tourists tend to stay away from beaches littered with plastic and users of the sea usually chose areas where they are less likely to encounter floating plastic as they’re swimming, canoeing or surfing in the sea.

Commercially important species such as fish, mussels, lobsters and crabs caught in various places around the world have all been shown to contain plastics. Most of the plastics stay in the animals digestive tracks, that we remove before consumption, which should limit the impact the plastic has on humans. However, there is more work to be done to fully understand the effect of consuming animals that have been feeding on plastics.

As we are finding plastics lower down in the marine food chain we also may see issues with our food supply. Microplastic has shown to decrease health in zooplankton, which is the food for our commercial fish. The number of fish destined for our plate could be restricted by their limited food supply. Two likely outcomes would be smaller fish or a reduction in their populations.

What changes are needed to minimize or eliminate the problem?

The simple solution to the problem is don’t put plastics in the sea. But there’s more to it than that.

A piece of plastic is ending up in the sea because either it’s been lost (large fishing nets) or the item has no value anymore and so there’s no need to keep it. So giving plastic a secondary value is one way to tackle the problem. If a currently single use plastic item could have a secondary and tertiary use then it is less likely to be discarded. Recycling, reusing, repairing or repurposing an item are common ways to give it a secondary value.

We need innovative solutions from engineers, materials scientists and designers to lead the way to giving plastics a value past its first intended use.